Researchers study pikas because they are an indicator of changes affecting the health of mountain ecosystems that humans depend on

A new study led by researchers at the University of Colorado Boulder carries a warning for one of the Rocky Mountains’ most iconic animals: the American pika, a small and fuzzy lagomorph often greeting hikers in Colorado with loud squeaks.

According to CU, the study draws on long-running surveys of pikas living in a single habitat about 10 miles south of Rocky Mountain National Park, Colorado in the Indian Peaks Wilderness.

Researchers discovered that ‘recruitment’ of juveniles to this site seems to have plummeted since the 1980s, meaning those populations are becoming dominated by older adults, with fewer juvenile pikas being born, or migrating in, to take their place.

The group published its findings recently in the journal Arctic, Antarctic, and Alpine Research.

Lead author of the study and a research associate at the Institute of Arctic and Alpine Research (INSTAAR) at CU Boulder Chris Ray explains why these aged pikas are a problem.

“It’s a fun encounter when you’re hiking on a trail in the Rockies and a pika yells at you,” Ray said. “If you don’t have that anymore, your experience in the wild is degraded.”

Ray added that scientists have long predicted that climate change might threaten pikas in the American West, noting one 2015 study predicted that pikas could disappear entirely from Rocky Mountain National Park by the end of the century.

According to CU, Ray and her colleagues can’t yet pinpoint the reason pika recruitment may be declining at this one location, but summers have been growing warmer at sites across the Rocky Mountains, a concerning bellwether for ecosystems that humans depend on.

“The habitats where pikas live are our water tower,” Ray said. “The permafrost, or seasonal ice, that’s underground here melts later in the summer and helps replenish our water supplies at a time when reservoirs are draining.”

In the current study, the researchers surveyed pikas living at the Niwot Ridge Long Term Ecological Research site north of Nederland, Colorado in 2004, and from 2008 to 2020. They then compared their results to similar surveys performed at the same site from 1981 to 1990.

According to CU, based on the researchers calculations, the proportion of pikas they trapped, that were juveniles, fell by roughly 50% from the 1980s to today, suggesting younger pikas could be growing rarer on Niwot Ridge.

Ray also noted her results support previous predictions that juvenile pikas may have trouble migrating through the Rockies as temperatures continue to warm. To cross from one mountain habitat to another, pikas first have to climb down in elevation, facing hot conditions in the process.

“Pikas are useful as a study system because they’re so visible and conspicuous, and they’re one way to get a handle on what changes are happening in alpine ecosystems,” Ray said.

Ray explained that pikas may be especially vulnerable to climate change, in large part because they can only survive in a narrow range of temperatures.

“Pikas don’t pant like a dog. They don’t sweat,” she said. “The only way they can release their metabolic heat is to get into a nice, cool space and just let it dissipate.”

Read the full article from CU Boulder here, and the compete study here.